A Breakdown in Basic-Materials Stocks

Normally, an 8.1% increase in a country's gross domestic product would be cheered by investors. But when the country in question, China, is viewed as the world's economic engine, the bulls tend to pull in their horns.

As they often do, markets anticipated last week's reported slowdown in China's economic growth and were already showing weakness. From copper to aluminum, industrial commodities and their related stocks were already on...